Alternating-current motor.



No. 725,596, PATENTED APR, 14, 1903. A. W. SGHRAMM.

' ALTERNATING CURRENT MOTOR.

APPLICATION FILED JAN. 9, 1903.

K0 MODEL.

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THE NORRIS PETERS co. Moro-muc wAsumumn. u,-

UNITED STATES PATENT OFFICE.

ADOLPH W. SOHRAMM, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO ELEOTRO DENTAL MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ALTERNATlNG-CURRENT M OTOR.

SPEGIFJIGATKON forming part of Letters Patent No. 725,596, dated April 14, 1903. Application filed January 9, 1903. Serialllo- 13 8,398. (No model.)

To a, whom it may concern:

Be it known that I, ADOLPH W. SOHRAMM, a citizen of the United States, residing in Philadelphia, Pennsylvania, have invented certain Improvements in Alternating-Current Motors, of which the following is a specification.

My invention consists in certain improvements in that class of motors designed to be operated by an alternating current of electricity, my object being to provide a motor especially adapted for use on circuits supplied with single-phase'alternating current, which while being of a simple construction shall be easily and efficiently controlled as to variations of speed and the direction of rota- I tion of its moving element. This object I attain as hereinafter set forth, reference being had to the accompanying drawing, in which the figure is a diagrammatic view of a motor constructed according to my invention, showing the various circuits and the connections thereof to current-supply mains.

In the drawing, A represents the frame of the motor, which is of a construction such that it will enable said motor to operate efficiently when supplied with an alternating current, there being in the present instance two field-magnets having windings a and an armature B, provided with a commutator b. Suitably supported either upon the motorframe or externally thereto is a coil of wire 0, wound upon a core a, of magnetic material, having one end connected to one of the supply-mains D and connected atsome point of its length to one end of the field-magnet.

winding a, the second end of said field-magnet winding a being connected to the second supply-main D.

I connect to certain of the convolutions of the coil 0 a series of taps 0, providing them with contact-terminals 0 preferably placed in the arc of a circle, at the center of which are pivoted t'wo electrically-independent contact-arms and a, one of these being connected by a Wire 0 to one of the armature or brush terminals 1) and the other bya wire 0 to the second armature-terminal 5 In addition to the contact-pieces 0 directly connected to convolutions of the coil 0, I provide a second set of contact-terminals 0 each of which is connected to one of the contact-bum tons 0 as shown in the figure, the central piece 0 of the series being somewhat larger than the others, so as tosimultaneously action to the armature of a higher electromotive force than would otherwise be possible. In operation if the supply-circuit be closed through the motor and both of the arms 0 and c are resting upon the central contactpiece 0 there will be no revolution of the armature as long as the brushes thereof are in the position shownin the figure. If, however, one of the contact-arms, as 0 be moved over the contact-pieces 0 the armature will begin to rotate and at a speed depending upon the distance said arm is moved from its central position. By again bringing this arm 0 to said central position and moving the arm 0 over the contact-points c the armature ,will be started and will be rotated in a direction opposite to that above noted.

I claim as my invention 1. v The combination with an electric motor having fieldwindings, an armature with a commutator and brushes, of an inductancecoil having a constant number of its convolutions connected with the field-windings and means for connecting the brushes at will to difierent ones of the convolutions of'said coil, substantially as described.

2. The combination with an electric motor having field windings, an armature with a commutator and brushes, of an inductancecoil permanently in series with said field-windings and means for connecting the brushes to different points of the said coil, substantially as described.

3. The combination of an alternating-current motor having field-windings, an armature with a commutator and brushes, with an inductance-coil having a series of contactpieces connected to certain of its convolutions and a contact-arm connected to one of the armatureterminals and placed to engage said contact-pieces, with means for con necting the other armature-terminal to different points of said coil at will, substantially as described.

4. The combination of an alternating-current motor, a coil connected to the field thereof, a series of contact-pieces electrically connected to ditferent points of said coil, witha plurality of contact-arms placed to engage said contact-pieces, and a connection between v each of said arms and the respective armature-terminals, substantially as described. 5. The combination with an alternatingcnrrent motor having field-windings, an armature with a commutatorand brushes, of a coilhavingaseriesofcontact-piecesconnected to certain of its convolutions, a second series of contact-pieces connected to the first set and two contact-arms connected respectively to the terminals of the armature and so placed that one of the same is free to engage the first set of contact-pieces and the other is free to engage the second set of the same, substantially as described.

6. In an alternatingcurrent motor, the combination of field-windings and an armature having a commutator and brushes with means for connecting one brush-terminal to the coil and means for connecting the second brush-terminal at will to different ones of the contact-pieces, substantially as described.

8. The combination with an alternatingcurrent motor having field-windings, an armature with a commutator and brushes, of a coil having a constant number of its convolutions connected to said field-winding and provided with a series of contact-pieces connected to different points of said coil, the connection of the said field-windings to the coil being made between the points of connection of certain of the contact-pieces, and means engaging said contact-pieces for placing more or less of the coil in circuit with the armature, substantially as described.

9. The combination with an alternatingcurrent motor having field-windings, an armature with a commutator and brushes, of a coil provided with a series'of connections to its convolutions, a series of contact-pieces for said connections, said coil being connected to the field and having a portion extending beyond the point of connection of the field provided with connections and contact-pieces, with a contact-arm connected to an armatureterminal for engaging said contactpieces, substantially as described.

10. The combination with an alternatingcurrent motor having field-windings, an armature with a commutator and brushes, ofa coil connected to the field-windings, a number of contact-pieces, means for connecting certain of said contacts to different points of the coil, means for connecting said latter contacts with others, with a pair of contact-arms connected to the armature and placed to engage said contact-pieces, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

ADOLPH W. SCHRAMM.

Witnesses:

R. RAUDENBUsH, Jos. H. KLEIN. 

